This invention generally pertains to the field of nickel plating. More particularly, this invention pertains to a nickel plating solution that can be used for ceramic composite materials, a plating method using this plating solution, and the products obtained thereby.
Nickel plating is widely used in the electronics industry as a ground for plating such as tin plating, solder plating, or gold plating. A strongly acidic nickel plating solution such as a vat bath, totally chloride bath, sulfaminic acid bath, or boron fluoride bath is conventionally used to deposit nickel in such applications. Even in electronic parts such as chip resistors or chip capacitors that are ceramic composites, a vat bath or sulfaminic acid bath is conventionally used to provide the nickel under layer for tin plating or solder plating.
In recent years, many new products that are ceramic composites containing transition metal oxides have been developed and are widely used in the electronic industry. Using the conventional strongly acidic nickel plating baths for plating special electronics parts that are ceramic composites containing transition metal oxides, however, has the problem that the ceramic part is corroded by the nickel plating solution. Consequently, reducing corrosion of parts easily corroded by conventional acidic nickel plating solutions has been attempted, and various plating solutions have been reported. All of these, however, are neutral to alkaline, contain a high concentration of potent complexing agents for maintaining nickel ions in the plating solution, and have the problems of reduced plating efficiency and reduced ease of operation. These plating baths also have the problem that even when only the electrodes of electronic parts having ceramic base materials require plating, plating spreads beyond these electrode parts to the surrounding ceramic parts, and thus damages the characteristics of these parts. In addition, just having a pH of about 4 to 7 causes corrosion of ceramic parts, reduces plating efficiency, reduces the power to keep nickel ions in the bath, and produces sediment in the form of hydroxides.